U.S. Pat. No. 4,394,481 and allowed copending application U.S. Ser. No. 453,029, now U.S. Pat. No. 4,419,489, both of which are hereby incorporated by reference, disclose chemically modified asphalts produced by reacting asphalt, a vinyl aromatic monomer, a rubbery polymer and an acrylamide. They are indicated to be of utility as protective coatings for various substrates including cementitious substrates. Solutions, as exemplified by a composition formed by reacting an AC-5 paving grade asphalt, styrene, Solprene 1205 C styrene-butadiene copolymer and dimethylaminopropylmethacrylamide, in a solvent of about 80 weight percent toluene and 20 weight percent of normal hexane, have demonstrated outstanding characteristics for the treatment of cementitious substrates, for example, the exterior surfaces of basements to provide a protective coating. The solutions have good shelf life; the solvent has good solvation properties; they dry at a desirable rate and show good wetout on the cementitious substrate. Upon evaporation of the solvent, the residual chemically modified asphalt shows good adhesion, has good elongation and elastic recovery, is tough and shows good cold temperature flex.
Unfortunately, the solvent employed does not satisfy all environmental regulations, and a new coating solution is consequently needed which will be environmentally acceptable and which will have the properties indicated above.
In accordance with the present invention, there is provided an environmentally acceptable protective coating solution having good shelf life, said solution comprising a major amount of an asphaltic material and a minor, but effective, solvating amount of cyclohexane based solvent, said solvent being an admixture of at least about 75% (wt) cyclohexane, 15%-25% toluene and up to 10% n-hexane. The asphaltic composition is a blend of a minor amount of asphalt having a viscosity of less than about 120,000 cps (at 140.degree. F.) and a major amount of the product produced by chemically reacting a vinyl aromatic monomer, asphalt having a viscosity of less than 120,000 cps (at 140.degree. F.), a rubbery polymer and an acrylamide. The solvent employed satisfies environmental regulations. The presence of asphalt as a blend with the above-indicated chemically modified asphalt is important in producing a solution having good shelf life, and, surprisingly, the presence of such asphalt as a blend with the chemically modified asphalt will not render the residual coating material unacceptable from an adhesion, elongation, elastic recovery, toughness or cold temperature flex viewpoint. The ability to include such asphalt with a chemically modified asphalt is also quite significant from a cost advantage viewpoint.